Various kinds of technology have been proposed for printing apparatuses such as color copiers and color printers to prevent forgery of paper currency and marketable securities and the like. For example, the technology disclosed in Japanese Patent Laid-Open No. 5-207261 is configured to processing to print on a paper sheet an image that is based on image data acquired by reading an original image and concurrently therewith to make a judgment regarding whether or not specified image data for which output should be prohibited is included in the image data. Such an apparatus is capable of judging that the image data includes specified image data during printing and executes invalidation processing that blots out the image that has been already printed on the paper sheet using white toner, and stops the mechanical operations or discharging the paper sheet. Thus, the apparatus prevents malicious use of the specified image that is printed.
However, in the conventional printing apparatus as described above, sufficient consideration has not been given to the correct processing to be performed when a command is received to print multiple copies of a certain specified image. More specifically, for example, in the case of a printing apparatus that is used by a plurality of users, in a case where one user inputs an instruction to print multiple copies of a certain specified image, when the mechanical operations are stopped, other users who are not attempting to print the specified image are inconvenienced and their print job is delayed.
In view of the above circumstances, there is a need for technology that makes it possible for a printing apparatus to perform appropriate processing when an instruction is made to print multiple copies of a specified image for which output should be prohibited.